TEMPE, Ariz. -- Tyrann Mathieu turned 21 on Monday, his life again at a crossroads.

In a text message that morning, the star-crossed former Heisman Trophy finalist said he had no plans for that night. Maybe he'd go visit with LSU/Arizona Cardinals teammate Patrick Peterson and his family. Maybe he'd hang out with his girlfriend.

It's a little thing, to be sure, that Mathieu would consider marking this particular milepost in his life with some quiet time. It doesn't signify all that much yet, not unless it's followed by a long stretch away from the wrong part of the news.

For now, it's simply another reason to buoy the hope that this is part of a new beginning for Mathieu, something most around the NFL agree he is looking for.

"He wants to change," one NFC personnel executive said. "But there's a big difference between wanting to and actually doing it. He has to change not only his lifestyle, but who he is."

Until now, to know who Mathieu is -- according to those around him, those who've studied him closely and those paid to assess him -- has been to know two completely different people.

There's Tyrann Mathieu the Football Player -- a tenacious athlete with born-to-play instincts and a passion for the game that made him one of the most reliable guys on LSU's roster when he was inside the team's facility. And there's Tyrann Mathieu the Problem Child -- whose sordid past became an excuse for everything he did, no matter what the cost, as he ran with the wrong crowd and became the most unreliable of student-athletes once he exited the building.

Changing, in this case, means fully embodying the guy who attracted everyone involved with LSU football (from his coaches and teammates down to the interns) during his time on the field -- and leaving behind the guy who was busted over and over again off of it.

"What I've had to learn is that everyone isn't out to get Tyrann."

-- Tyrann Mathieu.

Mathieu was still available to the Arizona Cardinals with the 69th overall pick in the 2013 NFL Draft not because NFL decision-makers don't believe he wants to change, but because they aren't sure he can.

So here Mathieu stands, with a career teetering before he has even played a professional snap. He knows it's time to seize control of his life and future. The question, then, becomes whether or not he can pull it off.

"I've been around the worst of the worst people, people you can't trust on any level, people that take advantage of you," Mathieu said over his cell phone late Saturday night. "I've always had that around, and what I've had to learn is that not everyone's bad. I'm learning that people are smiling because they're happy, not because they're out to get you. I had all these stereotypes about people, because I've been mad, and I have to let some of those things go.

"What I've had to learn is that everyone isn't out to get Tyrann."

The story of his childhood is now as familiar to Football America as it is sad. Mathieu was 2 years old when his father, whose own drug problem ended a promising football career, was sentenced to life in prison, having shot the boyfriend of another woman with whom he'd had a child. Mathieu was 5 when his mother gave him up. He lived with his grandparents, then an aunt and uncle, falling far off course along the way, just as his star was rising.

Mathieu earned the nickname "Honey Badger" because he played at LSU with a "don't care" kind of aggression. Of course, "don't care" could also describe the way Mathieu seemed to act in the rest of his college life, too. He was so good at football, and his past was so terrible, that he was extended a string of excuses -- and that string became the rope with which he nearly hung himself.

After being disciplined three times at LSU for positive drug tests -- and after failing several others -- he was thrown off the team. Mathieu did not participate in the 2012 campaign, marking the first time since grammar school that he'd missed an entire season of football, and his draft stock tanked.

Somewhat remarkably, he's received another shot, 1,500 miles away from his New Orleans home. And he wants to prove to everyone that he has no intention of blowing this one.

"I'm not a bad person," said Mathieu, who no longer wants to go by his old nickname. "I smoked marijuana, but marijuana should not beat me. The only thing I've wanted to do since I was 8 years old is play football. Why would I let something like marijuana keep me from that? Football is my only focus now. People can say anything they want about me. Once this dies out, I know I can shoot for the stars."

'I listened to the wrong people'

Get this part straight: When guys drop in the draft after failing marijuana tests, it's not necessarily the pot that scares teams; it's that, too often, the pot has gotten in the way of football, leading to questions about priorities.

Exactly how many drug tests Mathieu actually flunked at LSU is unclear. One AFC scout said Mathieu admitted to failing 10 before later saying he'd lost count. The NFC exec said Mathieu told his team that he had failed more than 12. An assistant coach for another AFC team said Mathieu put the number between 10 and 12. Mathieu, for his part, insists he wasn't privy to all the results while at LSU, and because he never had a real idea, declined to give clubs a solid number.

What we know is that he was put into regular testing after failing one test, was suspended for LSU's game against Auburn in 2011 for failing another and was dismissed after failing yet another in August 2012. He had many chances to clean up, but didn't -- and that's just part of what had NFL clubs concerned.

"It's not just him, but the family," the AFC coach said. "The family's upside down. There's a history of drugs there; it's been there since he was a kid. So everyone's concerned about whether or not he can maintain this. As a football player, no one's questioning that, what he can be. The question is, when is the other stuff gonna come back to haunt him? This is who he's been; it's kept pushing him down."

The assistant added that, while he trusts Mathieu's intention to separate from the negative influences in his life, "sometimes those people won't separate from you. Sometimes, it's not you. You can have the best intentions. But the people who have followed him around will still find a way to get to him. In some cases, this young man is all they've got. Some of the people he was with had never been to his games until they started talking about him like an All-Pro. Then, they showed up."

That goes a long way toward explaining why Mathieu trusts so few people, something that kept him going back to the places he knew best. Trouble was, those places also happened to be his own problem areas.

And it illuminates how, no matter where Mathieu was drafted, infrastructure was going to be key.

Tyrann Mathieu will begin his NFL career roughly 1,500 miles away from his troubled past in Louisiana.
(Bill Haber/Associated Press)

At least two clubs kept Mathieu off their draft boards primarily because of their proximity to Mathieu's native New Orleans. One team located further away had Mathieu listed as a high second-round talent who, because of the character flags, was draftable in the third round. Another, even further from Louisiana, had given him a solid second-round on-field grade and would've been willing to pull the trigger in Round 4.

Similarly, the Cardinals didn't make their decision in a vacuum. Geography was in their favor, as was the circumstance of having several key people already in the fold: Peterson, Kevin Minter (another ex-Tiger who was drafted by Arizona one round ahead of Mathieu) and defensive coordinator Todd Bowles, whose ex-wife's daughter is Mathieu's girlfriend. There's a larger picture here, too.

"It goes back to the fact that if you have 53 guys in your locker room, and if 25 of them are character risks, you'd have a real problem," Cardinals general manager Steve Keim said. "We feel like we've done a good enough job drafting and going through free agency to build some character -- not characters -- in our locker room, so that we can surround a few guys who may have had some issues in the past that deserve a second chance and an opportunity to succeed.

"You look at your locker room, and you have to feel like you have some stability in place, so you can take a chance here or there."

Some clubs got creative in trying to test Mathieu during the pre-draft process. The Cincinnati Bengals sat him down with Adam Jones to talk about the former first-round pick's checkered past. Mathieu said he's stayed in touch with the cornerback once known as "Pacman," and has used him as a resource.

The difference with Arizona was that so much was already in place.

Now, Mathieu says, "I understand my position in life. I've listened to all those people, lost my values. I'm focused on the positive things now. That's what I got away from. I listened to the wrong people at LSU."

'If anyone can handle this, it's Bruce'

Maybe the biggest asset Arizona has when it comes to helping Mathieu is one guy he didn't know before: Bruce Arians.

As one Cardinals source explained, the coach "is realistic, he's not sugarcoating it; he understands and he's honest with (Mathieu)." Another said that players "all trust this guy with their life; he's up-front and honest, and you can see the (relationship developing) between the two."

Arians is known league-wide for his ability to deal with strings-attached athletes, perhaps evidenced best by his work with quarterback Ben Roethlisberger and receiver Santonio Holmes in Pittsburgh. As the AFC coach put it, "Anyone who's dealt with Ben knows he can be aloof, he's different, but Bruce had an unbelievable relationship with him. ... If anyone can handle this, it's Bruce, and he's surrounded himself with coaches who know what he's about."

As the Cardinals spent a considerable amount of time with Mathieu at the NFL Scouting Combine, then at LSU, and finally back in Arizona before the draft, they came to see the potential for Arians to play a pivotal role.

"You can go back to when Bruce was one of the youngest college coaches in football, and he had an upstart program like Temple, and had a lot of kids who had off-field problems that he put in position to succeed," Keim said. "That's important to start at the top, with your head coach, where he not only believes in a guy, but understands how to put some structure in place to help him succeed."

There are tangible commitments Mathieu says he's willing to make to prove he knows the inherited risk goes both ways. He's ready to be accountable to Arians, Bowles, other assistants like Kevin Ross (the cornerbacks coach who will play a crucial part, according to those inside the organization) and his teammates. He's OK with random drug tests, and he will continue counseling.

But there's an intangible factor that might be more important: whether or not he can finally trust those closest to him.

"It's always been hard for me to trust people, and I'm working on that," he said. "I want to be able to trust my family, the people around me. I want to trust them; I don't want them to leave a negative vibe with me. ... I'm done with that. I'm happy now. They want me to be mad? I'm not. I'm happy. Even all the B.S. before the draft, I was still happy with myself, because I was taking huge strides."

There have been reasons to go the other way, even recently. Mathieu insists that a stomach virus stopped him from making pre-draft visits to the Seattle Seahawks (who nonetheless kept him on their board) and Houston Texans. In fact, he said the illness was still bothering him last week. And then there was the flier that surfaced on Mathieu's Twitter account one day prior to the draft. The dispatch advertised a draft party he was supposedly "hosting" and curiously referred to him as a first-round pick. Mathieu says he was on an airplane when the flier was released, stressing that he was completely unaware of the situation until a coach called him about it upon his landing. Per Mathieu, people working for his agent had access to his Twitter account, and they posted the unapproved flier on his timeline.

Still, he's pushing ahead with the plan to start trusting others, whether it's his high school coach, his adoptive parents, teammates like Peterson or LSU coach Les Miles, who was the first person to call him on draft night.

"How fast he plays, how aggressive he is, how he always goes for the ball -- that's what stuck out," Harrison said. "He's always around the ball. He loves to play football; you can see that. These teams sometimes want a guy that runs well or looks good. I want a football player. I know half the battle is teaching these kids how to play, and get them to play hard. This kid already has both those things."

"I actually think, this next time, things are gonna be different."

Harrison said he told the Patriots he hoped they'd draft Mathieu. Keim knows why. He saw the same things Harrison saw, which pushed him to move forward and inherit the risk -- after the Cardinals did a massive amount of background work.

The potential problems are obvious, but so is the talent. While Mathieu checks in at just 5-foot-9 and 186 pounds, running an unexceptional 4.5-second 40-yard dash, everyone can see that, as Harrison said, he's 100 percent football player.

"I don't know if I'd go out on a limb and say he could become the best corner in the draft," Keim said. "What I would go out on a limb and say is, he could be the best playmaker in the draft. He just has such unique skill, with instincts and getting his hands on the ball. He's so opportunistic on the field."

The onus is on Mathieu to be just as opportunistic off of it.

Last fall, while he was still on campus as a student and not a ballplayer, Mathieu watched the beginning of every LSU game -- but he couldn't finish any of them. He'd start blaming himself when Tigers safety Eric Reid would slip, or when a play that was there to be made wasn't, and he'd turn off the TV.

Before he left the football team, Mathieu wrote up a contract that he wanted LSU to give each of its defensive backs to sign. It covered, he said, "accountability, being where you're supposed to be, getting to your tutors and your classes and all those things, clearing all the hurdles, doing the extra film work. I don't want those dudes to get sidetracked like I did."

He already fell off the roadmap once, with an October arrest for marijuana possession, which ended his attempt to return to the Tigers in 2013. But he promised himself it wouldn't happen again.

It might seem that his Twitter handle (Mathieu_Era) still incorporates a nod to "Era Nation," the self-described group of New Orleans-area athletes and rappers with whom he ran in high school and college. However, in a text message Sunday, Mathieu said "Era" no longer refers to that; rather, it's about "this period of time I have to impact the world."

Most expect Mathieu to be fine in the short term. It's easier now. Sustaining it is the challenge.

"All of his problems are non-football-related," the first Cardinals source said. "But what happens if he has a big game? What happens if he has a bad game? That's the big thing we're looking out for."

That's where Mathieu plans to prove his growth.

"I actually think, this next time, things are gonna be different," Mathieu said. "I've gone through it; I understand it. I have a bad game, a good game, I understand I need to stay humble. And I know people throw that word around, but it's huge for me now. I have to stay humble. ... My biggest thing now is I'm able to reach out for help. I don't want to go back. My purpose in life is to play football."